Add parameter to adjust max message length in log listings

The parameter "max-message-length" can be specified in cgitrc, default value
is 60.

This affects the log message shown in repo summary and shortlog.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>
diff --git a/ui-log.c b/ui-log.c
index 725f49b..24d571d 100644
--- a/ui-log.c
+++ b/ui-log.c
@@ -23,7 +23,7 @@
 	char *qry = fmt("id=%s", sha1_to_hex(commit->object.sha1));
 	char *url = cgit_pageurl(cgit_query_repo, "commit", qry);
 	html_link_open(url, NULL, NULL);
-	html_ntxt(80, info->subject);
+	html_ntxt(cgit_max_msg_len, info->subject);
 	html_link_close();
 	html("</td><td>");
 	html_txt(info->author);